Electrically actuated variable electric time switch



y 1951 R. P. MOHN 2,553,829

ELECTRICAL-LY ACTQATED VARIABLE ELECTRIC TIME SWITCH Filed April 14, 1950 Z'Sheets-Sheet l 49 flake); P 7770/21/1 May 22, 1951 MOHN 2,553,829

ELECTRICALLY ACTUATED VARIABLE ELECTRIC TIME SWITCH Filed April 14, 1950 2 Sheets-$hee- 2 62 62/264184 Dev/be Patented May 22, 1951 UNITED ELECTRICALLY ACTUATED VARIABLE ELECTRIC TIME SWITCH Robert P. Mohn, Teaneck, N. J., assignor to Chester R. Mohn, Teaneck, N. J.

Application April 14, 1950, Serial N 0. 155,951

6 Claims. 1

This invention relates to a novel construction of electrically actuated time switch for controlling an electric circuit in which the switch is interposed so that electrically energized devices, connected to said circuit may be de-energized after different elapsed periods of time ranging up to or exceeding thirty-two hours.

An important object of the present invention is to provide such a time switch which is capable of being utilized with either direct current or alternating current and which is of extremely simple construction yet very efiicient in accomplishing its intended result.

A further object of the invention is to provide an electric time switch having a delayed action which is accomplished through a novel snap action movement to accomplish a positive and instantaneous interrupting of the electric circuit at the prescribed time and which includes a secondary make and break switch or circuit means which is likewise actuated by a snap action movement for accurately accomplishing the timing and operation of the device.

Various other objects and advantages of the invention will hereinafter become more fully apparent from the following description of the drawings, illustrating a presently preferred embodiment thereof, and wherein:

Figure 1 is a side elevational view, partly in vertical section illustrating one preferred construction of the time witch;

Figure 2 is a plan view thereof Figure 3 is a horizontal sectional View taken substantially along a plane as indicated by the line 3-3 of Figure l Figure 4 is a cross sectional view taken substantially along a plane as indicated by the line 4---| of Figure 1;

Figure 5 is a longitudinal sectional View taken substantially along a plane as indicated by the line 55 of Figure 1;

Figure 6 is a longitudinal sectional view, partially diagrammatic, taken substantially along a plane as indicated by the line |li of Figure l, and

Figure 7 is a diagrammatic view illustrating the electric circuit with which the switch is associated.

Referring more specifically to the drawings, the variable time switch comprising the invention is designated generally It and includes a frame, designated generally I l which is best illustrated in Figure 3 and which comprises a plate having laterally oifset substantially parallel longitudinally extending portions l2 and I3 and transversely extending portions l4 and 55. The portion I l constitutes an intermediate part of the plate and extends between the adjacent ends of the longitudinally extending longitudinally spaced portions I2 and I3. The portions 53 and it, which are disposed at right anglest one another, constitute the end portions'tthe frame ll. As seen in Figure 1, the end portion I3 has a part extending downwardly below the level of the bottom edge of the transverse portion l4 and a plurality of blocks NJ of insulating material are secured to said depending part of the frame portion l3 by fastenings l l. Another group of blocks [8 of insulating material are secured to the opposite sides of the frame portion I3 by additional fastenings I9 and above the level of the blocks l6.

As best illustrated in Figure 5, a bimetallic strip 2!] has one end clamped between two of the blocks It by said fastenings I! and its opposite free end extends longitudinally of the switch l0, passing beneath the frame portion M and to beyond the frame portion I5. A strip 2| of spring metal has one end clamped between two of the blocks it, in laterally spaced relationship to the bimetallic strip 2|! and extends therefrom to a point between the frame portions It and I5. Two strips 22 and 23 of spring metal are clamped between two of the blocks l6 and likewise extend toward but terminate short of the frame portion I5. The strip 23 is longer than the strip 22 and said strip 22 is in turn longer than the strip 2| and is disposed between the strips 2| and 23. The strip 2| is in turn disposed between the bimetallic element and the strip 22. A rigid bar 24 is clamped between one of the blocks I6 and the frame portion I3 and likewise extends toward the frame part IE but is substantially shorter than the strips 2 l, 22 and 23. A screw 25 extends threadedly through the bar 24 and has a cap 2% of electrical insulating material which extends through a slot 2! of the strip 23 and bears against the strip 22, as seen in Figures 1 and 5. The strips 2| and 22 are provided on their adjacent sides and near their free ends with contact points 28 and 29, respectively. A horseshoe-shaped spring 351 has one end engaging an opening 3| of the spring strip 23, between the free end of said strip and its slot 21 and the opposite end of the spring 30 extends through the slot 2'! and engages an opening 32 in the spring strip 22 and which is located near the free end thereof. The major portion of the spring 353 is disposed on the outer side of the strip. 23 or away from the strip 22 and said spring 30 is provided with reversed bends 33, adjacent its ends and which bends engage the openings 3| and 32. A relatively long pin 34 extends slidably through the bimetal element 28, near its free end, and has a shank end which is secured to the spring strip 23 adjacent the free end thereof and beyond the spring 30. The pin 3% is provided with a head'35 which is disposed on the opposite side of the-bimetallic element 2!] to the side thereof which is located adjacent strip 2|. A spacing sleeve 36 is disposed on the pin 34' between the bimetallic element 20 and strip'ZS. The shank of the pi 34 is of sufficient length so that the head: -spaced sufficiently from the sleeve 36 to allow the bimetallic element '23, which loosely engages the pin 34, to Swing relatively to the pin head 55 and sleeve 36 between its full and dotted line positions of Figure 5 without displacing the pin 34 laterally of the frame H. The strips ii, 252 and 23 are formed of electrical conducting material.

Referring particularly to Figure 3 and 6, a substantially rigid bar 31 has one end clamped between the frame portion l3 and the adjacent block it and extends therefrom toward the frame end l5 and terminates short thereof. The opposite end of the bar 31 is turned back to provide a loop 38 in which is anchored the ends of a pin as. The loop 33 and adjacent portion of the bar 31 is provided with a longitudinal slot sit), as seen in Figure l, to accommodate a cam, designated generally H which is swingably mounted on the pin 39. The cam M is notched to provide two oppositely facing abutment sur faces 42 and 33 which are disposed at oblique angles to one another. The cam A l is formed of electrical insulating material. The cam fil is provided with an outer surface 44 which is located more remote to the pivot 39 than another sur" face 45 thereof, for a purpose which will hereinafter become apparent. Two additional spring strips of electrical conducting material, designated i6 and ll are clamped at corresponding ends thereof between certain of the blocks l8 and extend to beyond the cam 4i and are disposed outwardly of the bar 3'1. The strip 55 is disposed between the strip ll and bar 3'! and said strips 46 and ll are provided at their free ends and on their adjacent sides with contact points it! and 39, respectively, which are normall disposed out of engagement when the spring strips 46- and 41 are in normal parallel relationship, as seen in Figure 3.

The frame portions [4 and I5 are provided with aligned bearings 59 and 5!, respectively, for journaling spaced portions of a shaft 52. The shaft 52, between the bearings 58 and 5! is provided with a right hand threaded portion 53 which is engaged by a nut 54. A plate 55 is secured to one side of the nut 54, in any suitable manner as by welding, and is provided with an arm or extension 55 which extends upwardly and which slidably engages in a longitudinally extending slot 5? of a cover plate 58 which is secured to the upper edge of the frame ll and which is preferably provided with apertured ears at its ends as seen at 59, whereby the switch I!) may be mounted on a suitable supporting surface with the cover plate 58 in either a horizontal. or vertical position and with the parts, previously described, extending into a reces or opening of such surface, not shown. It will be readily apparent that the extension arm 55 prevents the plate 55 and nut 56 from turning on the threaded shaft portion 53 so that when the shaft 52 is revolved, the plate and nut will move longitudinally thereof within the limits as provided by the slot 5?. The shaft is provided with a restricted threaded terminal Ell to receive a nut 5i which bears against the outer side of the frame part H4 and has a threaded opposite end 62, which is disposed substantially beyond the end it of the frame, which is adjustably engaged by a nut A ratchet wheel t l, all teeth of which face in the same direction is turnahly mounted on the unthreaded portion of the shaft 52 between the frame end it and nut and an expansion spring 65 is disposed onthe shaft 52 between the frame end lax-and theratchetwheelt l, .Alalrgc disk 66 having a knurled periphery is mounted on the shaft 52 between the nut E3 and a ratchet wheel M and a stronger expansion coiled spring 87 is mounted on the shaft 52 between the ratchet wheel and disk 8%. A friction washer 68 is mounted on the shaft 52 between the disk 56 and nut It will be apparent that the nut 63 may be adjusted on the shaft end 62 for varying the tension. on the spring E56 and El. The disk 6G is likewise turnably mounted on the shaft 52 and has a portion of its periphery extending through a transverse slot 69 of the cover plate 53.

An extension in of the free end of the bi.- metallic member 20 extends through a notch or recess "H in the front portion iii of the frame H, below the ratchet wheel 64 and has a pawl 72 secured thereto by a fastening l3 and which extends upwardly and at an oblique angle to engage the shoulders of the teeth of the ratchet wheel 6 which face counterclockwise. A holding pawl M is mounted pivotally on a pin 75 which projects outwardly from the frame portion and is yieldably urged into engagement with the teeth of the ratchet wheel 64 by a spring it to prevent said ratchet wheel from turning counterclockwise, as seen in Figure 4:.

Referring to Figure '7, a positive electrical conductor ll leads from a source of current supply to an electrical device or devices to be controlled by the switch it and energized by the current supply and a negative conductor 18 is likewise connected to the current supply and to the device or devices to be energized thereby. However, the negative conductor 58 is provided with a break, one end of which is connected at it to the resilient conductor strip and the other end of which is connected at 83 to the resilient conductor strip ll so that the circuit from the current supply to the control device or devices will be interrupted when the contact point is out of engagement with the contact point 49. A resistance wire and branch conductor 8i leads from the positive conductor if and includes a portion forming a resistance wire which is wound about the bimetallic strip The opposite end of the conductor 35 is connected to the resilient conductor strip 2i. Another branch conductor 82 extends between the conductor lit and the resilient conductor strip 22.

Assuming that the switch parts are in the positions as illustrated in Figure 1, in which positions the circuit as illustrated in Figure '7 will be broken due to the fact that the contact point 53 is out of engagement with the contact point if it desired to set the switch it so that the devices controlled thereby will be energized for a prescribed period, as for example thirty hours, the disk 63 is turned manually in a direction to turn the shaft 52 counterclockwise as seen in Figure l. The two springs and Bl between which the ratchet wheel 54 is gripped afford a less secure frictional engagement than the spring 6'! friction washer 63 between which the disk is is gripped so that haft will be turned with the disk and role ratchet wheel 64. This counterclockwise turning movement of the shaft 52 due to the right hand thread of its portion 53 will cause the nut 54 and plate 55, carried thereby, to be displaced from right to left of Figures 1, 2 and 3 since the arm will prevent the nut from revolving with the threaded portion 53. The outer sur face of the cover plate 58 may be graduated and calibrated in hours as indicated at in Figure I salons a side .ed aof itsgslot, 5? so that the arm 56 can function with said graduations as a pointer for visually indicating when the switch has been properly set to intrrupt the circuit after the prescribed time. In this case, the disk 66 would be turned until the arm 55 moved to position in alignment with the graduation mark 30. As the nut 54 commences its movement from right to left, a portion of the plate 55 will contact the cam surface 43 to turn the cam 41 on its pivot 39 in a counterclockwise direction as seen in Figure 3 to thereby move the surface 44 of the cam into engagement with the spring strip 55 and as said surface is disposed more remote to the pivot 39 than the surface 45, the spring strip 45 will be displaced downwardly, as seen in Figures 3 and 6 so that when the surface M is engaging flush against the spring strip 45 the contacts 48 and 49 will be in electrical engagement for closing the electric circuit. Assuming that the nut 54 and plate 55 have been moved to the left so that the arm 58 is in alignment with the hour graduation, as the circuit to the controlled device or devices has thus been closed by the contacts and 4e, such devices, not shown, will be energized and the resistance wire will likewise be energized to heat the bimetallic element 2i! due to the fact that the secondary circuit com prising the conductor 8!, conductor strip 2!, contact points 28 and 29, conductor strip 22 and conductor 82 is likewise closed since the contact points 23 and 29 are in engagement, as seen in Figure 7. As the bimetallic strip 2? is heated it will flex downwardly as seen in Figure 7, or upwardly as seen in Figure 5 or from left to right as seen in Figure 4.- and after a partial movement will contact the head so as to displace the pin 3:2 and resilient strip 23 upwardly as seen in Figure 5. When this occurs, the end of the spring so which engages the strip 23 will be moved across the plane of the strip 22 and when this happens, the spring as by a snap action will bias the free end of the strip 22 away from the strip 2| to disengage the contact 29 from the contact 28 to thus de-energize the secondary circuit of the resistance wire 8!. During this movement of the bimetallic mem ber 20 from left to right of Figure 4 while the resistance wire 8| is energized, its extension iii and the pawl 52 carried thereby will move to r the right as seen in Figure i a distance greater than the space between a tooth of the ratchet wheel 64 and less than the space between two of the teeth and as the ratchet wheel cc is pre vented from turning counterclockwise by the holding pawl 14, the pawl 12 will thus be moved relatively to the ratchet wheel to engage the tooth to the right of the tooth which is previously engaged. When he contact 29 is disengaged from the contact point 28 the resistance wire 8| is de-energized and as the bimetallic element 2 3 cools it swings to the left as seen in Figure l and in so moving turns the ratchet wheel 66 clockwise therewith a distance equal to the space between adiacent teeth of said ratchet wheel. Likewise, after a certain travel of the bimetallic element 26 from right to left of Figure 4 its extension l'ii will strike the spacing sleeve and move said spacing sleeve to the left as seen in Figure 4 and downwardly as seen in Figure 5 which will cause the strip 23 to be moved toward the strip 22 and in so moving, the end of the spring 38 carried thereby will move back across the plane of the strip 22. When this occurs, tlfdspring' 313 by a snap action will displace the strip 22 toward the strip 2i and return the contact 29 into engagement with the contact 28 to re-energize the resistance wire 8i so that the operation just previously described will be repeated. Each time that the ratchet wheel it is thus turned clockwise as seen in Figure 4 by the pawl '12, as pre viously described, it will turn the shaft 52 in the same direction due to the frictional couplingv provided between the ratchet wheel 6 and shaft 52 by the springs 55 and 61. This will cause the nut 54 and plate 55 to be displaced from left to right of Figures 1 to 3 and 6. As the nut 54 approaches the frame part I5, the plate 55 will pass the surface 43 and move into contact with the surface E2 of cam 4! to rock the cam on its pivot 39 in a clockwise direction as seen in Figure 6 and with the point 84 of the cam fulcruming on the spring strip 45. When this point 53 fulcrums and slides past a dead center position of the pivot 38 and surface 42, the resiliency of the strip 45 will cause the cam 4| to turn rapidly in a clockwise direction so that the strip 46 may spring away from the strip 4'? and into engagement with the surface 65, as illustrated in Figure 3, thus allowing the contact point 18 thereof to move out of engagement with the contact point and thereby interrupt the circuit to the device or devices energized by the current supply or source.

A number of sets of blocks 58, strips 45 and 41, bars 3'! and earns M may be utilized, with the cams 4! spaced longitudinally of one another so that the plate 55 in moving from left to right of Figures 3 and 6 may successively de-energize a number of electrical devices connected to the current supply at different intervals, the last circuit thus being interrupted being the one associated with the secondary circuit of the resistance wire 32. This will be readily accomplished since the plate 55 may continue to turn the cams 4| initially engaged thereby until the cam surface is disposed to contact the strip 45 thereby allowing the plate 55 to clear the abutment surface or shoulder 42 of said cams.

It is not essential that the disk 65 be frictionally coupled to the shaft 52 as said disk could be fixed thereto; however, by the use of the frictional coupling as described, any danger of damage of the parts by turning the disk 66 to too great an extent is eliminated since when the arm 56 engages the left hand end of the slot 51 a further turning of the disk 56 will merely cause it to slip and turn relatively to the shaft 52.

By adjusting the screw 2.5 the free end of the conductor strip 22 may be displaced toward or away from the strip to vary the extent of travel of the bimetallic element 25 before the secondary circuit 8!, 82 will be energized or deenergized and, accordingly, the time interval of the secondary switch 28, 29.

Various modifications and changes are contemplated and may obviously be resorted to, without departing from the spirit or scope of the invention as hereinafter defined by the appended claims.

I claim as my invention:

1. A variable electrically actuated time switch comprising a supporting structure, a shaft journaled in said supporting structure having a threaded portion, a member engaging said threaded shaft portion and slidably connected tothe frame structure to traverse the threaded shaft portion when the shaft is revolvedfia ratchet wheel connected to the shaft, a holding pawl to prevent rotation of the ratchet wheel in one direction, a bimetallic element supported at one of its ends by the supporting structure, a pawl on the free end of said bimetallic element engaging the ratchet wheel, a resistance wire adapted to be interposed in an electric circuit to be controlled by the time switch for heating the bimetallic element to move its pawl in one direction relatively to the ratchet wheel, a snap action switch interposed in the circuit of the resistance wire including a part engaged by the bimetallic element to interrupt the circuit of the resistance wire when the bimetallic element is heated and moved to a predetermined xtent, said bimetallic el dent and its pawl being displaced in the opposite direction by the cooling of the bimetallic element to cause the pawl to turn the ratchet wheel and shaft in the last mentioned direction and relatively to the holding pawl, said snap action switch having a part engaged by the bimetallic element when the bimetallic element is moved in the last mentioned direction for returning the snap switch to a circuit closing position to re-energize the resistance wire, a second switch supported by the time switch supporting structure including a resilient contact strip normally spring biased to a circuit interrupting position, said second switch including a pivotally mounted cam having a surface to engage said spring contact strip for maintaining it in a circuit closing position, and said cam having an abutment surface disposed in the path of movement of the member which engages and traverses the threaded shaft portion whereby said member upon reaching a predetermined point in its travel along the threaded shaft portion will engage the abutment surface to turn the cam on its pivot to move said strip engaging surface thereof out of contact with said resilient contact st 'ip to permit said strip to be biased by its resiliency to a circuit interrupting position to break the circuit in which the time switch is interposed.

2. A time swl ch as in claim 1, said ratchet wheel being frictionally coupled to the shaft, and a knob adapted to be manually actuated and connected to said shaft for turning the shaft in the opposite direction for displacing the member which engages the threaded shaft portion in the opposite direction to the direction in which it is moved by actuation of the ratchet wheel and by the pawl carried by the bimetallic member to reset the switch. and to turn the cam in the opposite direction to move said resilient contact strip back to a circuit closing position.

3, A time switch as in claim 1, said ratchet wheel being frictionally coupled to the shaft, and a knob adapted to be manually actuated and connected to said shaft for turning the shaft in the opposite direction for displacing the member which engages the threaded shaft portion in the opposite direction to the direction in which it is moved by actuation of the ratchet wheel and the pawl carried by the bimetallic member to reset the switch and to turn the cam in the opposite direction to move said resilient contact strip back to a circuit closing position, knob being frictionally coupled to the shaft by a more positive frictional coupling means whereby the ratchet wheel may be turned more readily relatively to the shaft than said knob.

4. A time switch as in claim 1, said ratchet wheel being frictionally coupled to the shaft, and a knob adapted tobe manually actuated and connected to said shaft for turning the shaft in the opposite direction for displacing the member which engages the threaded shaft portion in the opposite direction to the direction in which it is moved by actuation of the ratchet wheel and by the pawl carried by the bimetallic member to reset the switch and to turn the cam in the opposite direction to move said resilient con tact strip back to a circuit closing position, said knob being frictionally coupled to the shaft by a more positive frictional coupling means where by the ratchet wheel may be turned more readily relatively to the shaft than said knob, said coupling means of the ratchet wheel and knob including expansion springs mounted on the shaft between the ratchet wheel and a part of the supporting structure and between the ratchet wheel and one side of said knob, and a friction washer frictionally engaging the opposite side of said knob.

5. A time switch as in claim 1, said snap switch including a resilient contact blade, a spring strip actuated by swinging movement of said bimetallic member and moved thereby toward and away from said resilient contact blade, a bowed spring having one end connected to the resilient contact blade and its opposite end connected to said spring strip, said last mentioned end being movable with the spring strip, when actuated by the bimetallic element back and forth across the plane of the resilient contact blade for moving the blade by a snap action to a circuit closing or circuit interrupting position for energizing and de-energizing the resistance wire.

6. A variable electrically actuated electric cir cult controlling switch comprising a supporting st ucture, a shaft journaled therein and provided with a threaded portion, a nut engaging the threaded portion and slidably connected to the supporting structure for movement longitudinal by of the shaft when the shaft is revolved, a ratchet wheel connected to the shaft, a holding pawl to prevent rotation of the ratchet wheel in one direction, a bimetallic element connected to said supporting structure, an actuating pawl secured to a free end of said bimetallic element and engaging the ratchet wheel teeth, a secondary circuit adapted to be connected to an electric circuit controlled by the time switch including a resistance wire for heating the bimetallic ele ment, a snap switch interposed in the circuit of the resistance wire and actuated by the movement of the bimetallic element for intermittently energizing and de-energizing the resistance wire, said actuating pawl being oscillated by the bimetallic element for movement in one direction relatively to the ratchet wheel and for moving the ratchet wheel with the actuating pawl when iid pawl is moved in the opposite direction, a normally open switch controlling the first mentioned circuit including a spring contact normally biased to a circuit interrupting position, normally open switch being supported by supporting structure, a swingably mounted cam member having a surface to engage the spring contact to maintain it in a circuit closing position, said cam being dispos in the path travel of the nut when the shaf is turned by the ratchet wheel to cause the cam to be engaged and rocked by the nut to a position to release the spring contact to permit it to move to a circuit interrupting position.

ROBERT P. MOHN.

No references cited. 

